1. Field of the Invention
This invention relates to an improvement in machines for forming tiers of cartons in a predetermined pattern and loading or stacking successive tiers on a pallet to be transported from the machine. In one aspect this invention relates to an improved machine wherein the tiers are formed continuously and placed on the pallet or preceding tiers and when a pallet is loaded it is moved out of the elevator but an empty pallet is mechanically inserted into the stream of tiers at the top of the elevator between a loaded pallet and the tier-forming stationary plate.
2. Description of the Prior Art
The prior art is replete with devices for placing cartons upon pallets to load the pallets automatically. In many of the known prior art patents it is necessary to utilize elevator means for lifting successive tiers of cartons onto a pallet to produce a stack of cartons on said pallet. It has been found however to be advantageous to form the tiers of cartons and to move the same along the continued path to a position above the supporting pallet and then to lower the cartons onto the pallet and onto preceding tiers to stack a pallet with several tiers of cartons. The pallet is lowered after each tier is placed thereon to a position to receive a subsequent tier. After the pallet is completely loaded the same is moved out of the elevator and a second pallet is inserted to receive the next tier of cartons. If it is necessary to wait for the loaded pallet to be removed from the elevator and for the elevator to receive a pallet and raise the pallet to a loading position the continued stream of cartons to the accumulator forming the tiers is interrupted. It is thus advantageous to insert the empty pallets at the top of the elevator receiving the tiers.
One prior patent, U.S. Pat. No. 2,815,870, issued Dec. 10, 1957 to Herman Laub discloses an apparatus wherein the pallets are placed at the upper portion of the stacking column to receive cases placed thereon avoiding the necessity of the pallet being placed on the elevator and elevated to receive the first layer. The machine construction disclosed in U.S. Pat. No. 2,815,870, however has the tier forming machanism positioned directly over the elevator making it necessary for the flow of cartons to be interrupted as each row is formed and after each tier is formed. Further, the elevator structure utilized flight bars extending between endless chains such that each elevator comprised a pair of spaced flight bars which would be bridged by a pallet. In this construction the pallets have to be in nearly excellent condition without splintered edges or corners such that they could be supported only at opposite edges and carry the full load or stack placed thereon. The disadvantages of the prior art devices are thus the necessary interruption of carton flow and the lack of complete support beneath the pallet as the height of the stack increases. The first slows the production rate and the second means that many pallets become rejects for fear they will not be adequate supports in the loading elevator.
It is an object of the present invention to provide a "palletizer" or a pallet loading machine which will form tiers of cartons and stack the same on the pallet without interrupting the flow of cartons from a packaging, boxing or casing machine. The pallet loading machine of the present invention provides a novel pallet inserting machanism which supports the pallet in two loading positions prior to the same being placed upon the elevator such that continued movement of cases and tiers of cases is not interrupted. The tiers are stacked by being wiped off a stationary plate onto a moving plate which is then stripped from beneath the cartons placing them in the stack.